Hi All, 

My Focus CC3 2008 diesel, 

I'll start from the beginning, I've recently replaced the fuel filter due to not knowing the last time it was changed, Fitted ok then wouldnt start afterwards, Managed to draw enough fuel with vacuum pump to eventually get it started. Filled up tank - About 2 weeks later fuel reaching just 1/4 tank there's a loss of power followed by engine cut out, AA comes to my rescue, Drops car off at local garage, Local garage say the they bled the system and car was running for 40 mins no problems, I pick up car and get 2 miles down the road - same thing, Loss of power and cuts out, AA man comes and says air in the fuel line after the filter, Bypasses filter and shows me no air bubbles, Take it back to garage, Garage replaces the filter and runs it and says its ok but if it goes again it may be due to debris in system. Drove it home, the following day it does the same, Car gets towed home. Spoke to a couple of garages and one suggested poorly laid out fuel lines could have an airlock that sits in the system and when the pressure is lower/less fuel in tank it then becomes a problem, They also suggested that the fuel needs to be forced from the nozzle end of the system to basically push the airlock out. I get the Fuel doctor  out and he does something along those lines. I then fill the tank and drive it for 2 weeks untill today when it happens again, AA man comes out, fault reader says fuel pump not engaged or not working. I've had a different explanation from each person as to whether this car has a pump in the fuel tank or not, some say yes and some say no and it just relies on the high pressure side drawing fuel.  Some say when you switch the ignition on it should prime the filter/pump up to the filter.  This was ok before i touched it so my thinking is it is something i've created this issue or its a bad coincidence. 

 Well done if you've made it to the end of my saga !!   Does anybody know if this has a primary pump in the tank or have any ideas or suggestions ?   Thanks 

To confuse things, there is a pump fitted in the tank, but it's not used.

Presumably cheaper for Ford to bulk buy the fuel gauge units with pumps in at the time.

So you won't hear any priming with the ignition on.  There's almost certainly going to be a tiny hairline crack or pinprick hole in one of the plastic pipes.  It won't be easy to find as fuel won't leak out, just allows air in.

That's brilliant, It doesnt take much to confuse me at the best of times. 

So, This system relies completely on the high pressure side to do all the work. 

 

 

12 minutes ago, RichM75 said:

That's brilliant, It doesnt take much to confuse me at the best of times. 

So, This system relies completely on the high pressure side to do all the work. 

Yes, that's right.  The high pressure pump on these is slightly different to a conventional HP pump.  So there's no need for a tank lift pump.  

 

 

Thanks Tom, Appreciate the reply and info, I was struggling with the haynes manual trying to work it out, If i take it to a ford dealer , Do you know if they can they pressure test the fuel lines somehow? Sorry, Last question 🙂

I'll jump in with a quick answer while Tom is offline.

The kind of leak you are looking for is Tiny so small in fact that diesel fuel is too viscous to be able to pass through. Air can be drawn in to the system but the fuel is extremely unlikely to leak out.

Yes you could pressure test the fuel lines but the kind of pressure that would be needed to force the diesel out would burst the seals on the fittings. If you're sure that the air bubbles is only present after the filter then I'd suspect a problem with the filter housing / connector.

Thanks both for the help, It seems more likely to me that as i have changed the filter, i might have disturbed or aggravated something maybe the housing or connectors while changing the filter, Or possibly just a bad coincidence, I had no issues before i touched it lol, 

Thanks again for the help, Really appreciated.

Just a little update, Took the car to Ford dealer and they replaced the filter housing stating it was distorted? Collected the car and drove it for just over a month, Running the tank down to the low fuel warning twice, Then after a refill and down to 1/4 tank remaining the same problem returned,

Took it back to Ford, They bled the system and its running again but they are now saying the next step is to remove the tank to check for possible debris and to also replace fuel line to the filter.

From your previous comments about the fuel line having a pinprick hole or crack that may be the next thing to change, I'm just not enjoying the uncertainty of when it's going to let me down again,  How certain are you guys that the pump in the tank is designed not to be used ? Ford couldnt even tell me if it had a pump or not,   Any more thoughts or is the fuel supply pipe the most likely culprit?

Cheers

 

Richard

Does it only happen below 1/4 tank?  If so, that does point more towards the sender unit in the tank, either partially blocked* or perhaps the lower end of the pickup is split so it's only sucking in air when the level drops below the top of the split.

(* I had a blocked pickup once on a different car...but it was full of batter scraps as the car had been run on waste veg oil.  Shouldn't be any large debris in a modern fuel tank unless it's been refilled from a dirty Gerry can).

I'm 99% sure the 1.6 TDCI doesn't use the tank pump.  I am always open to being proved wrong though.

It's Only ever happened when it's been below 1/4 of a tank, This last time it was just over a quarter tank showing about 160 miles remaining, Having said that the 2 previous fill ups i ran it down to the warning light so just under 50 miles ish, And it seemed ok,  This is a 2.0 TDCI not sure if that makes a difference ?

Am i right thinking that the sender unit is just sensing fuel level? Is the fuel pickup part of the sender unit  or part of the pump,

Something blocking the fuel would tie in with when it happens i guess, Batter lol jeez , they couldve at least filtered it a bit before putting it in..

Just trying to think of the next easiest step, Do you know if dropping the tank out is relatively easy or a pig? I've seen some people cutting through the seat base to access the tank from the inside ?

Ah, could've sworn I read 1.6 somewhere!  The tank & sender is the same on both though.

The fuel filter and tank>filter pipes are different.

Sounds like the low level could be a coincidence but definitely worth keeping in mind for now.

I'm still fairly sure the 2.0 doesn't use the tank pump but maybe @iantt can confirm that.

 

The fuel sender does just sense fuel level with a float and resistor.  Though I use the term 'sender unit' to cover the whole plastic assembly.

The pickup uses concertina pipes like this (one inlet, one return) and they can crack around the concertina part.

 

Dropping the tank isn't too bad on a ramp.  It's very awkward on a driveway.  Obviously best to run the fuel down as much as possible first.

So the pickup essentially goes from that sender unit to the fuel filter, And if there is a pump you are thinking it would have no pipework connected.

So if that is the case, It could be cracked concertina pipe pickup?

possibly fuel line between sender unit and fuel filter having a pinhole or hairline crack?

or maybe some batter ??

Ive seen this as someones attempt to access, Would that be the pump or sender unit?

The pump is inside the sender assembly, it's covered by the white plastic on unit I pictured above. 

So on your picture, that is a sender unit which may or may not also have a pump within it.  There's no way to tell from the top.

Yes, the main fuel pipe runs from the top of the sender unit to the fuel filter.

Thanks Tom,

  Your help is really appreciated, How do you know so much about this ?

2008 Focus, were there any other fault codes ?  . Sorry, I’d always eliminate the common electrical issues first.

56 minutes ago, RichM75 said:

How do you know so much about this ?

I've owned many unreliable Fords.  

1 hour ago, RL123 said:

2008 Focus, were there any other fault codes ?  . Sorry, I’d always eliminate the common electrical issues first.

Both the AA and the Ford garage stated it read as unknown fault.  Yep it's a 2008 2.0 TDCI cc3

Faulty lead free soldering inside the instrument cluster and water ingress into the Fusebox/body module behind the glove box are issues on your model .They would generate lots of diagnostic trouble codes including ones starting with ‘u’.

many posts on this if you do a search on the forum.

Thanks, I'll check fusebox and cluster, Removed the sender unit at the weekend, No pump inside just fuel level sensor, Checked the pipework and no visible signs of cracking  or splits, Blew the inlet/out through with compressor,  All looked clean and the tank looked clean. Refitted it all and it started fine, I've filled the tank and i'm going to try to keep using it and keeping the fuel above half a tank as it's only ever been a problem at 1/4 tank or lower.  At least we know there is definitely no pump in the tank.